System and method for boosting torque output of a drive train

Abstract

An engine speed detector detects an engine speed of an engine having a baseline torque versus engine speed curve. A torque sensor detects an engine torque of the engine. A data processor determines if the detected engine speed is within a first speed range and if the detected engine torque is within a first torque range. A motor controller activates an electric motor to rotate substantially synchronously with a corresponding engine speed associated with the detected engine torque in an electric propulsion mode in accordance with a supplemental torque versus engine speed curve if the detected engine speed is within the first speed range and if the detected engine torque is within the first torque range. The supplemental torque versus engine speed curve intercepts the baseline torque versus engine speed curve at a lower speed point and a higher speed point.

1. A method for boosting a torque output of a drive train, the method comprising:
 detecting an engine speed and engine torque of an engine having a baseline torque versus engine speed curve; 
 determining if the detected engine speed is within a first speed range and if the detected engine torque is within a first torque range; and 
 activating an electric motor to rotate substantially synchronously with the engine speed within the first range in an electric propulsion mode in accordance with a supplemental torque versus engine speed curve if the detected engine speed is within the first speed range and if the detected engine torque is within the first torque range, the supplemental torque versus engine speed curve intercepting the baseline torque versus engine speed curve at a first lower speed point and a first higher speed point. 
 
   
   
     2. The method according to  claim 1  further comprising:
 permitting a transition between the baseline torque versus engine speed curve and the supplemental torque versus engine speed curve only at the first lower speed point and the first higher speed point. 
 
   
   
     3. The method according to  claim 1  wherein the supplemental torque versus engine speed curve is generally parabolic and has an enhanced peak torque between the first lower speed point and the first higher speed point. 
   
   
     4. The method according to  claim 1  wherein the enhanced peak torque exceeds the baseline torque at any engine speed. 
   
   
     5. The method according to  claim 1  further comprising:
 determining if a state of charge of an energy storage device indicates that the energy storage device requires recharging; and 
 deactivating the electric motor for a time period if the stage of charge indicates that the energy storage device requires recharging. 
 
   
   
     6. The method according to  claim 1  further comprising:
 determining if a state of charge of an energy storage device indicates that the energy storage device requires recharging; and 
 placing the electric motor in a power generation mode for a time period, rather than the electric propulsion mode. 
 
   
   
     7. The method according to  claim 1  further comprising:
 determining if the detected engine speed is within a second speed range and if the detected torque is within a second torque range; and 
 activating an electric motor to rotate substantially synchronously with the engine speed within the second speed range in an electric propulsion mode in accordance with a second supplemental torque versus engine speed curve if the detected engine speed is within the second speed range and if the detected torque is within the second torque range, the second supplemental torque versus engine speed curve intercepting the baseline torque versus engine speed curve at a second lower speed point and a second higher speed point, distinct from the first lower speed point and the second higher speed point. 
 
   
   
     8. The method according to  claim 7  further comprising:
 permitting a transition between the baseline torque versus engine speed curve and the second supplemental torque versus engine speed curve only at the second lower speed point and the second higher speed point. 
 
   
   
     9. The method according to  claim 1  wherein the detecting of the engine torque comprises detecting the engine torque during deactivating of the electric motor. 
   
   
     10. The method according to  claim 1  wherein the detecting of the engine torque comprises detecting the engine torque while the electric motor is in an active state and deducting a torque contribution of the electric motor from an aggregate torque based on the baseline torque versus engine speed curve and the supplemental torque versus engine speed curve at an applicable operating point.